3DES Key Components

Question

I need to encrypt/decrypt data using 3DES. the Keys shared with me are in the form of;

Component 1 = 11111111111111111111111111111111

Component 2 = 22222222222222222222222222222222

KVC = ABCD1234

I need to create 3DES Key from the above components, or K1,k2,k3 sub keys,

I understand sub keys are 16 bytes long, however these are 32 bytes long.

Please share the procedure to create 3DES key.

Answer 1

Transform the clear components in to byte arrays using HexStringToByte standard method. Pass the 3 byte arrays to the method below. You can verify your results at http://www.emvlab.org/keyshares/. Here are sample data:

• cc1: 447FC2AA6EFFFEE5405A559E88DC958C
• cc2: 1086F0493DB0EFE42EDF1BC99541E96F
• cc3: D1C603D64D1EDC9D3CA78CD95D168E40
• result key: 853F31351E51CD9C5222C28E408BF2A3
• result key kvc: 1E49C1

public static byte[] buildKey(byte[] cc1, byte[] cc2, byte[] cc3) {
  byte[] result = new byte[cc1.length];
  int i = 0;
  for (byte b1: cc1) {
    byte b2 = cc2[i];
    byte b3 = cc3[i];
    result[i] = (byte)(b1 ^ b2 ^ b3);
    i++;
  }
  return result;
}